The existent maintenance apparatuses for dental handpieces are of the type as proposed in Japanese Patent No. 2587001. The apparatus of this type has an adaptor to be connected to the proximal end side of a handpiece so that a washing liquid and a lubricant supplied through the adaptor can be fed to the rotary member of the cutting tool of the handpiece. However, in this maintenance apparatus, the washing liquid and the lubricant supplied to the handpiece are both fed to only the turbine and the bearing thereof, but not to the chucking structure which is located on the center of the turbine and detachably holds the cutting tool, which leads to a problem that the dirt and abrasion filing in the chucking structure can not be removed.
There is another proposal for hand-operation maintenance of medical handpieces, using a special-purpose nozzle equipped on the tip end of a spray bomb. In case of this method, an operator feeds a maintenance fluid to the bearing of a handpiece but pays less attentions to the maintenance of the chucking structure thereof which is very important for safety, than the maintenance of the bearing thereof. Accordingly, the operator feels it troublesome to feed the washing fluid to the chucking structure of the handpiece or often forgets it. Therefore, the maintenance of the chucking structure of the handpiece is not surely carried out. In addition, since the chucking structure is not communicated with the bearing of the handpiece, the maintenance fluid is fed to only the bearing but not to the chucking structure. Further, because the chucking structure made up of a plurality of metallic or resinous components is subject to contamination and foreign matters, such a disadvantage gives serious influence on the function of the chucking structure for holding the cutting tool. When the maintenance fluid is fed to only the bearing in the handpiece, for example, in the air turbine, the bearing can keep its normal high-speed rotation since the maintenance fluid is fed thereto, while the chucking structure tends to deteriorate earlier prior to the bearing, since the maintenance of the chucking structure is insufficient. For this reason, it becomes hard for the chucking structure of the handpiece to firmly hold the cutting tool, which results in a failure in the air turbine. Thus, the air turbine tends to be broken earlier before the handpiece has completed its service life. In another case where a hand-operation maintenance is made on a handpiece, the amount of a maintenance fluid becomes insufficient or excessive, so that the maintenance of the bearing and the chucking structure becomes insufficient, or so that the maintenance thereof costs higher. In addition, feeding an excessive amount of the maintenance fluid induces problems in that such a fluid is adhered to the handpiece so that the operator or an assistant slips one's hand on the grip of the handpiece and fails to hold it, and in that the hand of the operator or the clothes thereof, or the face of a patient or the clothes thereof are stained.
To overcome these problems, the present invention is intended to provide a maintenance apparatus which performs effective and reliable maintenance on the bearing and the chucking structure of a medical handpiece.